JPH1131843A - Lighting device for light emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the brightness of a light emitting diode from being affected by the voltage of a battery and maintain the brightness at a fixed level without using a booster circuit, by detecting the voltage of a power supply, intermittently turning on a switch element to light the light emitting diode, and increasing the ratio of the light emitting diode being turned on with the reduction of the voltage of the power supply. SOLUTION: When a microcomputer 1 commands to enter into a previously set status by a signal from each part of a gas apparatus, for instance, a status where a burner is lighted, a transistor 4 is turned on and a light emitting diode 3 is lighted, and where the burner is turned off, the transistor 4 is turned off and the light emitting diode 3 is turned off. Instead of using a booster circuit, the voltage of a power supply 2 is monitored and sufficient brightness can be obtained when the voltage is sufficiently high even when a conduction time is short. Therefore, an on signal from the microcomputer 1 to the transistor 4 is converted into a pulse signal of a prescribed frequency or more, and the on-time is shortened and the off-time is lengthened. When the voltage of the power supply 2 reduces, the on-time, i.e., light emitting time, is lengthened, preventing brightness deterioration. Thus, the brightness of the light emitting diode 3 is prevented from being affected by the variation of the power supply voltage without using a booster circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for lighting a light emitting diode mounted on a battery-powered device.

[0002]

2. Description of the Related Art In a gas appliance such as a gas water heater or a gas table, a battery may be used as a power supply for operation. In such a gas appliance, a light emitting diode is attached to the gas appliance in order to know the operating state of the gas appliance, and the light emitting diode is turned on when a predetermined operating state is reached. In order to turn on and off the light emitting diode, a switching element such as a transistor is connected in series to the light emitting diode, and the switching element is turned on to energize the light emitting diode to turn on the light emitting diode.

On the other hand, the brightness (brightness) of a light emitting diode becomes darker when the voltage of a battery as a power supply decreases. Conventionally, in order to keep the brightness of the light emitting diode constant irrespective of the voltage of the battery, a booster circuit that outputs a constant voltage even if the input voltage fluctuates is mounted on the light emitting diode, and the light emitting diode emits light even when the battery voltage drops. A constant voltage is always applied to the diode so that the luminance does not change.

[0004]

In the above-mentioned conventional apparatus, since a booster circuit is provided, the cost of the gas appliance is increased due to the cost of the booster circuit. Therefore, an object of the present invention is to provide a lighting device that maintains the luminance of a light-emitting diode constant without using a booster circuit and without being affected by battery voltage.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, according to the present invention, a switching element is connected in series to a light emitting diode attached to a battery-powered device, and the state of the device is a predetermined state. In a case where the switching element is turned on to turn on the light emitting diode, a voltage detecting means for detecting the voltage of the power supply is provided, and the light emitting diode is turned on by intermittently turning on the switching element, and the power supply voltage is turned on. Is characterized by increasing the rate at which the switching element is turned on while the light emitting diode is illuminated, as the light emitting diode is turned on.

When the voltage of the power supply is high, if the blinking is performed in a state in which the rate at which the switching element is turned on is reduced, the luminance is high but the lighting time is short one time. If the rate of turning on increases as the voltage of the power supply decreases, the luminance is low but one lighting time is prolonged. By doing so, the brightness of the light emitting diode, which makes the continuously blinking state visible to the naked eye, does not change. The light emitting diode is actually blinking, but if the blinking cycle is short, there is no problem because the naked eye recognizes that the light is on.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference numeral 1 denotes a microcomputer for controlling the operation of a gas appliance or the like, and operates using a dry battery as a power supply 2. In the present embodiment, the power source 2 is formed by connecting two dry batteries in series. The voltage of the power supply 2 is input to the A / D port of the microcomputer 1, and the microcomputer 1 constantly monitors the voltage of the power supply 2. Reference numeral 3 denotes a light emitting diode, and a transistor 4 serving as an opening / closing means is connected in series with a resistor for limiting a current, and is connected to the power supply 2 in the series state. The transistor 4 is opened and closed by a signal from the microcomputer 1. When the microcomputer 1 is set to a predetermined state based on signals from various parts of the gas appliance (not shown), for example, the burner is turned on, the transistor 4 is turned on to turn on the light emitting diode 3 and the burner is extinguished. In this state, the transistor 4 is turned off and the light emitting diode 3 is turned off. By the way, in the conventional device, the voltage of the power supply 2 is not monitored by the microcomputer 1 and the booster circuit is connected to the light emitting diode 3. In such a conventional device, the transistor 4
When it was turned on, it was kept on continuously until it was turned off next. In the present invention, instead of using the booster circuit, the voltage of the power supply 2 is monitored, and the energization control described below is performed according to the voltage of the power supply 2.

In FIG. 2, E represents a change in the voltage V of the power supply 2 over time T. When the voltage of the power supply 2 is sufficiently high (3 V or more), sufficient luminance can be obtained even if the energization time is short. Therefore, the ON signal from the microcomputer 1 to the transistor 4 is a pulse signal having a frequency equal to or higher than a predetermined frequency, and the ratio of the ON time to the OFF time by the pulse signal is 3: 7. When the voltage V of the power supply 2 decreases and falls between 3.0 V and 2.5 V, the luminance of the light emitting diode 3 decreases. The light emission time is lengthened instead of decreasing. When the voltage V of the power supply 2 further falls and becomes 2.5 V to 1.8 V, the above ratio is changed to 7: 3, and the decrease in luminance is compensated for by further increasing the light emission time.

In the above embodiment, the voltage of the power supply 2 is set to 3.0 V and 2.0 V in order to facilitate understanding of the present invention.
It has been described that the ratio of the on time and the off time is divided into three types, divided into three sections with 5V as a boundary,
The voltage of the power supply 2 may be further divided into more categories, and a plurality of types of the above ratios may be set. Further, the ratio may be continuously changed in conjunction with a change in the voltage of the power supply 2.

[0010]

As is apparent from the above description, according to the present invention, when the light emitting diode is turned on and off by using a battery as a power source, the luminance of the light emitting diode depends on the fluctuation of the voltage of the power source without using a booster circuit. Not affected.

[0011] Further, the conventional one also requires an opening / closing means for causing a light emitting diode to extinguish a fire, and the present invention adds a new part by effectively utilizing the opening / closing means required by the conventional one. The booster circuit can be omitted without the need.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating switching of energization time due to a decrease in the voltage of a power supply.

[Explanation of symbols]

 1 microcomputer 2 power supply 3 light emitting diode 4 transistor

Claims (1)

[Claims] 1. An apparatus in which a switching element is connected in series to a light emitting diode attached to a device powered by a battery, and when the state of the device is in a predetermined state, the switching device is turned on to turn on the light emitting diode. Providing a voltage detecting means for detecting the voltage of the power supply, and turning on and off the switching element to turn on the light emitting diode,
A lighting device for a light-emitting diode, characterized in that the rate at which the switching element is turned on during the lighting of the light-emitting diode increases as the voltage of the power supply drops.